Acrylic acid is a chemical for which the worldwide demand is high, about 5 Mt/a (million ton per annum) in 2008 and possibly about 9 Mt/a by 2025. A known route for the production of acrylic acid comprises the oxidation of propene into acrolein (propenal) and then oxidation of the acrolein into acrylic acid. See for example “On the partial oxidation of propane and propene on mixed metal oxide catalysts” by M. M. Bettahar et al. in Applied Catalysis A: General, 145, 1996, p. 1-48. The overall reaction stoichiometry for this route is as follows:CH2═CHCH3+1.5O2→CH2═CHCOOH+H2O.
A disadvantage of the above-mentioned route for the production of acrylic acid is that two oxygen atoms have to be introduced into the propene by the use of an oxygen containing gas at high temperature (about 350° C.) and with release of a large amount of heat (about 600 kJ/mol). A further disadvantage is that propene has to be used which may be derived from propane. Both propene and propane are currently only readily available as fossil feedstocks and are therefore not renewable.
WO 2012/154450 describes a process in which monopropylene glycol is converted to propanal, which in turn is converted to propenal, which is then oxidized to acrylic acid.
Eva Diaz, et al., Chem. Sus. Chem., 2012, 3(9), 1063 discloses a process for producing acrylic acid comprising preparing acrolein by oxidation of 1,3-propanediol. The acrolein is then oxidized to acrylic acid.
C3-oxygenates contain 3 carbon atoms and 1 or more oxygen atoms. There exist a number of C3-oxygenates which may contain 1, 2 or 3 oxygen atoms and which may be formed as undesired (by)products in certain production processes such as biomass conversion processes. Such biomass conversion process may be the aqueous phase reforming of sugars, as disclosed by N. Li et al. in Journal of Catalysis, 2010, 270, p. 48-59. Examples of such C3-oxygenates are: 1-propanol, monohydroxyacetone, 2-hydroxypropanal, 3-hydroxypropanal, dihydroxyacetone and 2,3-dihydroxypropanal.
Consequently, there is a need in the art to valorize C3-oxygenates in general, which may be formed as undesired (by)products in certain production processes such as biomass conversion processes.